3D printing for photonics: a British initiative
Current techniques used to produce optical fibre preforms, the piece of glass from which an optical fibre is drawn, give a consistent structure along the length of the preform but make it difficult to control the shape and composition of the fibre in 3D.
This is the limitation that Professor Jayanta Sahu, together with his colleagues from the University of Southampton’s Zepler Institute and co-investigator Dr Shoufeng Yang from the Faculty of Engineering and Environment, hope to go past.
While today’s micro-structured fibres are made by manually stacking several smaller glass capillaries or canes together to form the preform, the new techniques investigated would rely on the laser sintering of very fine glass powders, layer-by-layer.
While discussing this new initiative with eeNews Europe, Professor Sahu admitted he was starting pretty much from scratch.
“First, we’ll have to figure out the finesse of the glass powders and the power level of the lasers used to melt or coalesce the particles during the sintering process in order to achieve optical-grade quality preforms” he said.
“Once we’ll have determined the optimum particle size and sintering process, we’ll want to tailor the dopant concentrations during sintering by mixing different doped glass powders to be dispensed by the 3D printer’s nozzles”.
But what Sahu finds the most exciting, is the level of precision that could be reached in the full 3D of a preform (instead of today’s only radially assembled preforms with the same longitudinal structure).
“First, you could build larger preforms, in excess of 100mm so all the features would scale down to a greater extent when the fibre would be drawn” Sahu explained, “but you could also envisage new built-in optical or photonic functions along the length of the preform”
In the long run, the idea would be to build a 3D-printable CAD library of dopant profiles and photonic blocks that designers could use to make special-purpose optical fibres or even photonic chips.
Silica fibre drawing tower in the Zepler Institute cleanroom complex.
The researcher is well aware that numerous challenges lay ahead, including the high melting temperature of the glass (over 2000˚C in case of silica), the need for precise dopant control and refractive index profiles for accurate waveguide geometries.
As part of the project, funded by the Engineering and Physical Sciences Research Council (EPSRC), the researchers will be working with three companies: ES Technology (Oxford, UK), a provider of laser material processing systems; Fibercore (Southampton, UK) a supplier of specialty fibre; and SG Controls (Cambridge UK) a leading manufacturer of optical fibre equipment.
Visit the Zepler Institute at www.zeplerinstitute.com